Production of metals



July 29, 195s c. M. OLSON PRODUCTION 0F METALS Filed Mrch 16, 1954 a a,lliiflzws/m CARL MARCUS OLSON INVENTOR.

BY mit( me AGENT invention. cient atlinity for oxygen to permit thereduction to go to completion with the production of elemental titanium.

United States Patent s i PRODUCTION OF METALS Carl Marcus Olson, Newark,Del., assignor to E. I. du Pont de Nemours and Company, Wilmington,Del., a corporation of Delaware Application March 16, 1954, Serial No.416,517

9 Claims. (Cl. 204--64) This invention relates to the production andpuriiication of metals whose oxides are unsuited for ordinarypyrometallurgical reduction processes. More particularly, it relates tothe production of such metals by reduction of the metal oxide by amolten salt reducing agent.

In order to describe clearly the novelty and benefits of my inventionthe problems attending the production of pure metals will be analyzedusing titanium metal as representative of the metals alluded to aboveand which are not obtained in satisfactory high purity by the usualpyrometallurgical furnacing methods. Pure titanium metal has becomeincreasingly important because of its strength, low density, andsuperior resistance to corrosion. The large scale commercialexploitation of this metal is gravely hindered by the multiplicity ofunit steps required in the existing commercial processes. One presentprocess employs the reaction between titanium tetrachloride andmagnesium. Both of these reactants require many process steps for theirseparate preparation and purification. The additional reduction stepsinvolved in the preparation of titanium thus puts titanium in the classof expensive metals exploited only for very special uses. The manyfavorable properties possessed by titanium will be utilized only whenthe metal is produced at lower cost bya more economical process.

The above situation emphasizes the desirability of ohtaining a moredirect production process. One method to achieve this goal is thereduction of titanium oxide directly to the metal. Processes for theproduction of pure titanium oxide in terms of hundreds of tons per dayare operating commercially. Prior methods for the reduction of titaniumoxide by an active metal, i. e. alkali metals, alkaline earth metals andaluminum have not realized the goal of low cost metal. Of the abovegroup of reductants, calcium is technologically preferable but strontiumand barium are also operable by the methods of my Calcium, strontium andbarium have sutli- Unfortunately in prior methods, it has been necessaryto employ at least twice the stoichiometric quantity of calcium in orderto obtain metal of suicient purity for prac- 'tical utility. The priormethods contemplated reaction vessels of the bomb Type which utilizedheavy structural design and ditlicult closure means. The use of metalliccalcium as a reactant also leads to serious disadvantages becausecalcium metal (also barium and strontium) unlike sodium and magnesium isvery expensive to prepare. It is not produced in the common type ofelectrolytic cell and even in the xspecial equipment now used theefficiency is very poor with the result that the price of calcium isabout ten times that of magnesium. In prior methods impurities, of whichnitrogen is most deleterious, were introduced with the calcium in spiteof attempts to scrape or otherwise mechanically remove the contaminants.The products obtained from these methods were mixed with the by-productsof the ICC reaction. Hence a separation entailing the removal of calciumoxide by lixivation of the reaction mass in an acid was utilized.

One object of my invention is to overcome the disadvantages of presentprocesses for the production of metals such as titanium, zirconium,vanadium, and chromlum by utilizing a more easily obtainable rawmaterial. A further object is to eliminate the many ditiicultiesencountered in prior methods using calcium, strontium and/ or barium asthe reducing metal. A still further object is' to provide a moreeconomical process for the production of said metals having a minimumoxygen content. Further objects will become apparent from the followingdescription of my invention.

These and other objects are accomplished by my invention relative to theproduction of metals selected from the group consisting of titanium,zirconium, vanadium and chromium by reduction of an oxide of said metalswith a compound of an alkaline earth metal of the group calcium, barium,strontium, which comprises commingling said oxide with a molten saltreducing agent comprised of a halide of said alkaline earth having adeiiciency of halogen from the normal dihalide, causing relativemovement between the reactants to achieve intimate contact and dissolvethe by-product alkaline earth oxide, and subsequently recovering thereduced metal from residual reaction components. A particular embodimentof my invention relates to a process for the preparation of titaniummetal by reduction of an oxide of titanium with a separately preparedreducing agent involving calcium which comprises partially reducingmolten calcium chloride, commingling the molten active calcium compoundwith said oxide, causing relative movement between the reacting phases,continuing the reduction until the oxygen is substantially all removedfrom said oxide and subsequently recovering titanium metal from residualreaction components.

The molten salt reducing agent mentioned above as an essential part ofmy process may be suitably prepared in an electrolytic cell which may beoperated as an integral part of the reduction apparatus. The alkalineearth metal halides when subjected to electrolysis yield a halogen gasand the alkaline earth metal is collected around the cathode. This metaltends to dissolve into the molten salt up to about 15% of the saltcomposition and the nature of this solution has been discussed in apublication of the United States Atomic Energy Commission in 1950entitled, A Chemistry and Metallurgy of Miscellaneous Materials. Editedby L. L. Quill (McGraw-Hill Book Company, Inc.). While it is notdefinitely proven that a compound such as CazClZ exists, it seemsabsolutely certain that the metal dissolves in the salt phase on amolecular scale. These authors (see pages l1 and 12) lean to the viewthat a strong interaction between the metal ions of the salt and themetal molecules exist. In view of these considerations I am referring tothe metallic reducing agent as a subhalide of an alkaline earth metal.

ln the preferred embodiment of my invention wherein titanium metal isproduced from oxide of titanium while employing calcium chloride as themolten salt, the molten salt is passed through an electrolytic cellprior to its contact with the titanium oxide being reduced. The ilowthrough the cell should be from the anode zone to the cathode zone andthence to the zone wherein the oxygen is to be removed from thetitanium. At the anode, oxygen is removed from the calcium chloridemelt, while at the cathode free calcium is generated which becomesdissolved in the calcium chloride to give my reducing agent. The latteris passed on to contact with the metal oxide for removal of its oxygenand calcium oxide is formed at this point. The latter while in solutionin the calcium chloride is passed on to the cell and while surroundingthe anode of the cell the oxygen content is removed as carbon monoxideaccompanied by consumption of the carbon. anode and thus the oxygen isremoved from the system. The cyclic ow of the calcium chloride iscontinued until the oxygen has been removed from the metal oxide. It isthus seen that the reaction is carried out in an apparatus employingseveral zones wherein specific changes of the system are taking place asthe removal of oxygen from the salt at the anode, the production ofsubchloride at the cathode and the removal of oxygen from the metaloxide in the reduction chamber proper. The molten salt as it leaves thelatter contains calcium oxide, While the salt entering this zone issubstantially free of oxygen and is laden with calcium which ismolecularly dispersed in the molten salt.

Figure l is a ow diagram of my preferred process. Vessel 1 represents anelectrolytic cell wherein the reduced alkaline earth metal salt isproduced by electrolysis. This molten salt flows from vessel 1 to thereactor S through line 3 irnpelled by well known means 4. The metaloxide, e. g., titanium oxide charged to the reactor via line 8 isrepresented by 6. The molten salt ows into intimate contact with thetitanium oxide charged into reactor and after reaction exits throughline 7 to return to vessel 1. In vessel 1 the oxygen, removed fromthetitanium oxide by the molten reducing agent and present therein as anoxide of the alkaline earth metal, is stripped from the said moltenagent by electrolysis. This step produces the reduced calcium compoundi. e., calcium molecularly dispersed in normal calcium chloride andcarbon monoxide by the interaction of the oxygen with the carbon anodeof the cell during electrolysis. As the electrolysis proceeds tocomplete removal of oxygen from the anolyte, chlorine in admixture withthe oxide of carbon may be evolved along with the increase in the amountof the molecularly dispersed calcium within the molten salt.

Figure 2 is a section view of an apparatus whereby my invention may becarried into effect. The cylindrical iron reaction vessel 1 is providedwith a shelf 2 upon which rests a cylindrical iron container 3 providedwith a perforated bottom. The charge of titanium oxide material to bereduced 4 is contained in this basket. The charge of molten salt 5 iscontained in vessel 1' and is circulated from the bottom up through line6' back into the upper portion of vessel `1 by impeller 7.

Impeller 7 is driven through a belt and pulley arrangement by a motorsituated apart from the heated area; these are not shown in drawing. Aseal of solidified salt 8 between vessel 1 and container 3' is obtainedand maintained by cooling element 9.

The lid 11 is bolted to vessel 1 and has a gasket 10 of heat resistantmaterial. Thermowell 12 of metal pipe,

for temperature measurement in cell, extends through lid into the moltensalt. Product gases leave the reaction vessel through vent pipe 13.Carbon anodes 14 and iron cathode 15 are insulated from the apparatus bysleeves 16. Electric power is supplied to these electrodes by well knownmeans not shown in drawing. The iron cathode 15 consists of a watercooled upper section terminating in a perforated iiat circular plate 17.The cooled tube provides and maintains a frozen salt mass 18 whichinsulates this portion of the cathode from the anode region of the cell.rlfhe vessel 1 is surrounded by a furnace 19, extending slightly abovethe level of the molten salt. The molten salt may be drained from theapparatus by removing cap 23 from line 20, turning oit cooling water tocoils 22, and melting frozen salt seal 21.

In practicing the method of my invention, a charge of titanium oxide tobe reduced or crude metal to be refined is placed in the basket 3'. Thischarge is preferably `in the form of small particles generally notexceeding 3/Za `of an inch in size. The charged basket 3 is then placedin vessel 1'. A charge of molten salt, preferably calcium chloride isheated to about 900 C. and then poured into vessel 1 up to a levelslightly above the impeller discharge pipe. Immediately after chargingthe vessel the furnace 19 is heated and brought up as rapidly aspossible until the molten salt mass is about 850 C. as measured by athermocouple in thermowell 12. During this heating-up period, lid 11 isinstalled with the electrodes retracted above the salt level. As soon asthe temperature indicates a molten state, the cooling water into 9 and22 is turned on, the impeller 7' is tested for freedom of movement, theelectrodes 14 and 15 are immersed to the correct level and outlet 13 isconnected to a noxious gas vent system. Then the impeller motor isturned on and electrolytic power supplied to the electrodes. Directcurrent having a voltage of from 25-35 volts is suitable for the processand optimum value will depend on apparatus design. The temperature ofthe molten salt is kept at about 850 C. by regulating the amount of heatsupplied from the furnace. Electrolysis is continued until oxides ofcarbon are not detected in the gases given olf from the cell. Oncompletion of the run the electric power is turned olf from theelectrodes and stirring motor, the electrodes are retracted, the furnaceheating source turned ol and cooling water into 9 turned off. When thetemperature of the molten salt decreases to about 800 C., the salt isdrained from the vessel into an iron pot as described above. Thetitanium metal is protected by a coating of salt and the atmospherewhich is maintained inert until the mass has cooled somewhat.

The basket is then removed from the vessel and the titanium metalproduct is then washed substantially free of calcium chloride bylixivation with water. The metal product is then discharged from thebasket into a tray and dried in an oven to remove adherent water. Theparticulate metal product then can be treated by prior art means toobtain massive shapes or utilized as is for suitable applications.

Specific results using the above manner for the application of myinvention are given in the following examples.

Example I A quantity of pressed pellets, about 1A inch in size, of pureTiOg were prepared in a pellet press and 1800 g. were charged to thebasket of an apparatus as shown in Figure 2. The molten calcium chloridewas added to the vessel until about 25 kg. was charged. The treatmentproceeded as hereinabove described using a bath temperature of about 850C. The electrolysis was run for approximately 8 hours until theevolution of oxides of carbon ceased. The apparatus was cooled asdescribed above and the titanium metal extracted free of calciumchloride with water and dried at C. The metal product analyzed 99.5+% Tiand .10% O2. The metal after melting in a vacuum arc furnace was foundto have a Vickers hardness number of 187.

Example II The application of my invention to the removal of smallamounts of oxygen from contaminated titanium metal is herein described.A charge of 3360 grams of titanium metal contaminated with 4% oxygen wasplaced in the basket of the apparatus as described, Figure 2. Thetitanium metal was in the form of small lumps, approximately 1/8 to 1Aof an inch in size. The charge of calcium chloride was prepared asbefore and the elcc trolysis operation carried out. After 3 hours thereaction was complete and the current was stopped. The product waswashed and dried as before with a final weight of 3200 grams of titaniummetal being obtained. This was analyzed to be 99.5+% Ti and .14% O2.After melting a sample in a vacuum arc furnace the metal had a Vickershardness number of 210.

The above examples serve to illustrate modes of applicatio of myinvention and are not meant to limit the application of my inventionthereby. Equivalent methods of operation of my invention may be moresuitable on a larger scale. In this' manner a separation of theelectrolysis cell from the titanium oxide reduction section would allowone cell to serve a number of reduction units. The reduced calciummolten salt product being impelled from the electrolysis cell through amass of titanium oxide held in a reduction unit and then the used moltensalt returned back to the electrolysis cell for renewal of the reducedcalcium content. My invention treats titanium oxygen compounds ofvarying ratios from titanium dioxide to low oxygen content titaniummetal. A titanium alloy may be produced by the use of a titanium rawmaterial such as metal ttanates example iron titanate). As a molten saltelectrolyte, l prefer to use anhydrous calcium chloride, although othersalt mixtures may be utilized, said mixture comprising a halide ofcalcium, barium and strontium either alone or admixed. The preferabletemperature range for operation of my invention is from about 800 to1000 C. depending upon the electrolyte used although the process may becarried out at a higher temperature, the limit depending upon equipmentconsiderations and the volatility of reaction components. Manymodifications in the electrolysis apparatus are possible to one skilledin this art but it suices to say it is preferable to arrange the cell sothat cathode products are held apart from-the gases being evolved at theanodes in order that secondary reactions which defeat the purpose ofelectrolysis are prevented. Many modifications for the reduction vesselare also possible but herein also some principles are observed, in thatit is necessary that adequate commingling of the titanium oxide and thereduced calcium -molten salt take place. Also the calcium oxide which isproduced must be removed from the metal product and this is achieved byrelative movement of the two phases, the one solid and the other molten.The molten salt stream as it leaves the cathode compartment of the cellmay be suitably forced downwardly through a bed of titanium oxide to bereduced in a continuous manner and passed through the bottom of thesupport for the titanium oxide at its trip back toward the anodecompartment of the cell. Such a mode of operation provides that themetal oxide to be reduced is continually contacted with a fiowing streamof the reducing salt and as the calcium oxide content increases it moveson toward the anode compartment of the cell for the release of theoxygen while the calcium content of the salt is increased simultaneouslyin the cathode compartment. It is thus seen that this method ofoperation provides a highly effective reducing agent which issubstantially free of oxygen and that this high temperature reducingagent may be continuously` replenished in a closed cyclic system.

' The chemical principle involved in the series of reactions are notclearly understood but the following theory leads to a reasonableexplanation. In the electrolysis of molten calcium chloride at atemperature near the melting point of calcium a cathode product isobtained which does not separate out elemental calcium but -instead adark colored substance appears to form irnmediately in the vicinity ofthe cathode. In a recent publication by Cubicotti, J. A. C. S. 71, 2149(1949), he postulates that a compound Ca2Cl2 is formed with probably anion of the Ca2++ type i. e. one Ca++ ion bonded to or combined with eachcalcium atom. Thus he observed solutions having the equivalent of aboutcalcium dissolved in calcium chloride at 900 C. A molten-saltalkalinefearth halide is thus obtained in which the alkaline earth metalion is in a reduced state or in other words in which the salt has adeciency of halogen from the normal dihalide. I have found that thisreduced calcium will react with titanium oxide to produce titanium metaland calcium oxide. Calcium oxide is soluble to the extent of severalpercent in molten calcium chloride and when this molten solution ispassed through an electrolytic cell fitted a carbon or graphite anode atthe usual calcium cell conditions of temperature and voltage the anodeis consumed and the oxygen content of the anolyte is reducedsubstantially to zero. The results with barium and strontium aresubstantially equivalent to that achieved with calcium.

The process which I have outlined by example depends on the removal ofoxygen from titanium by reaction with a molten chloride of calcium whichhas often been referred to as the subchloride of calcium Ias well assolution of calcium in calcium chloride. This calcium compound isextremely high in its reducing -action and is able to break the bondbetween titanium and oxygen. Calcium oxide and the normal calciumchloride are thereby formed simultaneously with the production ofsubstantially oxygen-free titanium metal. The oxide of calcium issoluble in calcium chloride and pound or the resulting titanium metalproduc-t is continuously treated with the molten calcium chloride, thecalcium oxide is dissolved and withdrawn from the desired metal product,leaving the latter in substantially pure condition. The calcium `oxidecontaining salt melt is recirculated to the cell for regeneration of theCa2Cl2, or the subchloride if `one chooses to use this nomenclature. Thecell effluent comprising a mixture of Ca2Cl2 and CaClZ may be passedcontinuously through the cell and into contact with the titanium productundergoing reduction. The reaction is in reality the use of electriccurrent in the removal of oxygen from titanium, using calcium chlorideas a vehicle for carrying out the operation with transfer of the -oxygento the electrolytic cell as calcium oxide dissolved in calcium chloride.Further chemical reaction takes place at the carbon anode by theformation of car-bon monoxide and the overall chemical reaction may beconsidered to be the removal of oxygen from metal oxide by carbon in atwo step operation.

The use of pressed titanium oxide pellets was mentioned in Example -Lbut it is understood that `one may produce substantially pure titaniummetal by reducing an artificially prepared titanium oxide product suchas is commercially produced in titanium pigment plants and generallyreferred to as calciner discharge. Such a product may consist of coarselumps which work well in the hereindescribed process. `Other commercialproducts may be substituted. Other metal oxides or mixtures of oxideswill give the corresponding metals and alloys.

The subhalides of calcium, strontium, and barium have been designated asuseful in the process for the removal of oxygen from titanium oxide orother oxygen containing compositions `of titanium, zirconium, vanadiumand chromium. It is desirable that the reduction be carried to the pointwhere the product contains not more than .2% oxygen and preferably toless than 0.1% oxygen. It is known that the ductility varies with theoxygen content and the most desirable products have been found toanalyze not more than .05% which can be reached by my novel process bycontinuing the contact of the titanium or other starting oxide materialwith `the molten reducing agent or cell effluent until the oxygencontent is thus depleted.

In the examples outlined above, l have shown an operation in whichcalcium chloride is circulated to la reactor containing a static bed ofoxygen containing titanium composition and continuously displacing thechloride as its reducing power is spent by fresh cell efliuent in acyclic manner through the regenerating cell and the reduction zone. Itis essential tothe invention that there be relative movement between themolten salt reducing agent and the titanium oxide in order to remove thecalcium oxide reaction product and to constantly expose the productundergoing reduction to the molten salt possessing the required reducingpower, It Iis obvious that this relative movement between the titaniumundergoing treatment and the molten salt may be carried out in otherways and when the titanium oxygen com.

accordingly, the Ainvention should be considered as covering suchequivalent operations.

This series of reactions is utilized by my invention in a novel mannerto produce titanium metal from easily obtainable and inexpensive rawmaterials. The extreme reactivity of calcium metal is obtained withoutthe necessity of separately preparing and purifying the diicultyobtained reducing agent. The metal reduction reaction is carried outeasily in a simple manner and results in a product having only watersoluble material to be removed. This obviates the past disadvantages ofcalcium reduction wherein the calcium oxide was retained with the metaland extensive acid leaches were then required. Finally the product hasthe required low content of embrittling impurities and has desirablephysical properties.

This application is a continuation-in-part of my copending application,Serial No. 193,813, filed November 3, 1950, now abandoned.

I claim as my invention:

l. A process for the production of a metal selected from the groupconsisting of titanium, zirconium and vanadium from an oxidiccomposition thereof which comprises circulating a molten halide saltcomposition of an alkaline earth metal selected from the groupconsisting of calcium, barium and strontium initially through an -anodeportion and a cathode portion of an electrolytic cell to partiallyreduce said salt and dissolve therein the free alkaline earth metalformed, thence passing the resulting molten salt mixture into a suitablechamber conning the oxidic composition, passing the molten salt etiiuentfrom the chamber to the anode portion of said cell Where it is beingsubjected to electrolytic action with evolution of carbon monoxide byinteraction of the oxygen content of the salt with a carbon anode,continuing the ow of salt composition into the cathode portion of thecell where the alkaline earth metal content of the salt composition isbeing restored, passing the cell effluent to the said chamber tocomplete the cyclic system, continuing the circulatory movement untilcarbon monoxide is no longer evolved at the anode and recovering themetal of high purity from the chamber.

2. A process for the production of titanium metal from an oxygencontaining titanium composition which cornprises circulating a moltenhalide compound of an alkaline earth metal selected from the groupconsisting of calcium, barium and strontium initially through an anodeportion and a cathode portion of an electrolytic cell to partiallyreduce said salt and dissolve therein the free alkaline earth metalformed, thence passing the resulting molten salt mixture into a suitablechamber confining the said titanium composition, passing the molten salteiuent from the chamber to the anode portion of the cell where it isbeing subjected to electrolytic action with evolution of carbon monoxideby interaction of the oxygen content of the salt with a carbon anode,continuing the flow of salt composition into the cathode portion of thecell where the alkaline earth content of the salt composition is beingrestored, passing the cell etlluent to the said chamber to complete thecyclic system, continuing the circulatory movement until carbon monoxideis no longer evolved at the anode and recovering the high puritytitanium metal from the chamber.

3. A process for the production of titanium metal from an oxygencontaining titanium composition which cornprises circulating a moltencalcium chloride salt composition initially through anode portion and acathode portion of an electrolytic cell to partially reduce saidchloride and dissolve therein the free calcium formed at the cathodethence passing the molten salt mixture into a suitable chamber conriingthe said titanium composition, passing the molten salt et'uent from thechamber to the anode portion of said cell where it is being subjected toelectrolytic action with evolution of carbon monoxide by interaction ofthe oxygen content of the salt and with a carbon anode, continuing theflow of salt composition into the cathode portion of the cell where thecalcium content of the salt composition is being restored, passing thecell el'luent to the said chamber to complete the cyclic system,continuing this circulatory movement until carbon monoxide is no longerevolved at the anode and recovering the titanium of high purity from thechamber.

4. A process for the removal of oxygen from titanium metal having oxygenintimately associated therewith which comprises circulating a moltenhalide salt composition of an alkaline earth metal selected from thegroup consisting of calcium, barium and strontium ini tially through ananode portion and a cathode portion of an electrolytic cell to partiallyreduce said salt and dissolve therein the free alkaline earth metalformed, thence passing the molten salt mixture into a suitable chamberconfining the titanium metal from which oxygen is to be removed, passingthe molten salt eiuent from the chamber to the anode portion of the cellwhere it is being subjected to electrolytic action with evolution ofcarbon monoxide by interaction of the oxygen content of the salt with acarbon anode, continuing the flow of salt composition into the cathodeportion of the cell where the alkaline earth content of the saltcomposition is being restored, passing the cell el'liuent to the saidchamber to complete the cyclic system, continuing the circulatorymovement until carbon monoxide is no longer evolved at the anode andrecovering the titanium metal ot high purity from the chamber.

5. A process for the removal of oxygen from titanium metal having oxygenintimately associated therewith which comprises circulating a moltencalcium chloride salt composition initially through an anode portion anda cathode portion of an electrolytic cell to partially reduce saidchloride and dissolve therein the free calcium formed, thence passingthe molten salt mixture into a suitable chamber confining the titaniummetal from which oxygen is to be removed, passing the molten salteffluent from the chamber to the anode portion of said cell where it isbeing subjected to electrolytic action with evolution of carbon monoxideby interaction of the oxygen content of the salt with a carbon anode,continuing the flow of salt composition into the cathode portion of thecell where the calcium content of the salt composition is beingrestored, passing the cell eiuent to the said chamber to complete thecyclic system, continuing this circulatory movement until carbonmonoxide is no longer evolved at the anode and recovering the titaniumof high purity from the chamber.

6. A process for the production of zirconium metal from an oxygencontaining zirconium composition which comprises circulating a moltenhalide compound of an alkaline earth metal selected from the groupconsisting of calcium, barium and strontium initially through an anodeportion and a cathode portion of an electrolytic cell to partiallyreduce said salt and dissolve therein the free alkaline earth metalformed, thence passing the resulting molten salt mixture into a suitablechamber conlining the said zirconium composition, passing the moltensalt eiuent from the chamber to the anode portion of the cell where itis being subjected to electrolytic action with evolution of carbonmonoxide by interaction of the oxygen content of the salt with a carbonanode, continuing the flow of salt composition into the cathode portionof the cell where the alkaline earth content of the salt composition isbeing restored, passing the cell efuent to the said chamber to completethe cyclic system, continuing the circulatory movement until carbonmonoxide is no longer evolved at the anode and recovering the highpurity zirconium metal from the chamber.

7. A process for the production of vanadium metal from an oxygencontaining vanadium composition which comprises circulating a moltenhalide compound of an alkaline earth metal selected from the groupconsisting of calcium, barium and strontium initially through an anodeportion and a cathode portion of an electrolytic cell to partiallyreduce said salt and dissolve therein the free alkaline earth metalformed, thence passing the resulting molten salt mixture into a suitablechamber conning the said vanadium composition, passing the molten salteluent from the chamber to the anode portion of the cell where it isbeing subjected to electrolytic action with evolution of carbon monoxideby interaction of the oxygen content of the salt with a carbon anode,continuing the ow of salt composition into the cathode portion of thecell Where the alkaline earth content of the 'salt composition is beingrestored, passing the cell etlluent to the said chamber to complete thecyclic system, continuing the circulatory movement until carbon monoxideis no longer evolved at the anode and recovering the high purityvanadium metal from the chamber.

8. A process for the production of zirconium metal from an oxygencontaining zirconium composition which comprises circulating a moltencalcium chloride salt composition initially through anode portion and acathode portion of an electrolytic cell to partially reduce saidchloride and dissolve therein the free calcium formed at the cathodethence passing the molten salt mixture into a suitable chamber conningthe said zirconium composition, passing the molten salt eluent from thechamber to the anode portion of said cell where it is being subjected toelectrolytic action with evolution of carbon monoxide by interaction ofthe oxygen content of the salt and with a carbon anode, continuing theow of salt composition into the cathode portion of the cell where thecalcium content of the salt composition is being restored, passing thecell euent to the said chamber to complete the cyclic system, continuingthis circulatory movement until carbon monoxide is no longer evolved atthe anode and recovering the zirconium of high purity from the chamber,

10 9. A process for the production of vanadium metal from an oxygencontaining vanadium composition which comprises circulating a moltencalcium chloride salt composition initially through anode portion and acathode portion of an electrolytic cell to partially reduce saidchloride and dissolve therein the free calcium formed at the cathodethence passing the molten salt mixture into a suitable chamber confiningthe said vanadium composition, passing the molten salt euent from thechamber to the anode portion of said cell where it is being subjected toelectrolytic action with evolution of carbon monoxide by interaction ofthe oxygen content of the salt and with a carbon anode, continuing theflow of salt composition into the cathode portion of the cell where thecalcium content of the saltcomposition is being restored, passing thecell elluent to the said chamber to complete the cyclic system,continuing this circulatory movement until carbon monoxide is no longerevolved at the anode and recovering the vanadium of high purity from thechamber.

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES Journal of the American Chemical Society, vol. 71 (1949),pages Z149 2.153, article by Cubicciotti et al,

1. A PROCESS FOR THE PRODUCTION OF A METAL SELECTED FROM THE GROUPCONSISTING OF TITANIUM, ZIRCONIUM AND VANADIUM FROM AN OXIDICCOMPOSITION THEREOF WHICH COMPRISES CIRCULATING A MOLTEN HALIDE SALTCOMPOSITION OF AN ALKALINE EARTH METAL SELECTED FROM THE GROUPCONSISTING OF CALCIUM, BARIUM AND STRONTIUM INITIALLY THROUGH AN ANODEPORTION AND A CATHODE PORTION OF AN ELECTROLYTIC CELL TO PARTIALLYREDUCE SAID SALT AND DISSOLVE THEREIN THE FREE ALKALINE EARTH METALFORMED, THENCE PASSING THE RESULTING MOLTEN SALT MIXTURE INTO A SUITABLECHAMBER CONFINING THE OXIDIC COMPOSITION, PASSING THE MOLTEN SALTEFFLUENT FROM THE CHAMBER TO THE ANODE PORTION OF SAID CELL WHERE IT ISBEING SUBJECTED TO ELECTROLYTIC ACTION WITH EVOLUTION OF CARBON MONOXIDEBY INTERACTION OF THE OXYGEN CONTENT OF THE SALT WITH A CARBON ANODE,CONTINUING THE FLOW OF SALT COMPOSITION INTO THE CATHODE PORTION OF THECELL WHERE THE ALKALINE EARTH METAL CONTENT OF THE SALT COMPOSITION ISBEING RESTORED, PASSING THE CELL EFFLUENT TO THE SAID CHAMBER TOCOMPLETE THE CYCLIC SYSTEM, CONTINUING THE CIRCULATORY MOVEMENT UNTILCARBON MONOXIDE IS NO LONGER EVOLVED AT THE ANODE AND RECOVERING THEMETAL OF HIGH PURITY FROM THE CHAMBER.